Battery charge/discharge control device, battery charge/discharge control method, and hybrid working machine with battery charge/discharge control device

ABSTRACT

A battery charge/discharge control device which performs battery charge/discharge control in a working machine with a battery capable of storing electric energy generated by a generator motor coupled to an engine and driving the generator motor or at least one of other electric actuators by the stored electric energy and a controller which controls a distribution of the electric energy among the battery, the generator motor, and the electric actuator, wherein the controller performs the charge/discharge control in which the electric energy of the battery is discharged when the engine is driven and recharging to the battery is permitted on a condition that a state in which an engine speed is equal to or lower than a predetermined engine speed is maintained for a predetermined time after the battery is completely discharged.

FIELD

The present invention relates to a battery charge/discharge controldevice, a battery charge/discharge control method, and a hybrid workingmachine with a battery charge/discharge control device, where the hybridworking machine may store electric energy (the electric energy isreferred to as a charge in the description below) generated by agenerator motor mechanically coupled to an engine in a battery and maydrive the generator motor by the electric energy stored in the batteryso as to drive the engine by assisting the output thereof or may drivethe other electric actuator by the electric energy stored in thebattery, and the hybrid working machine includes a controller whichcontrols a distribution of the electric energy between the battery andthe generator motor or between the battery and the other electricactuator, thereby performing the battery charge/discharge control.

BACKGROUND

Recently, a hybrid working machine has been practically used in which anengine and a generator motor mechanically coupled to the engine areprovided as a driving source and an electric actuator is rotationallydriven by the electric energy generated by the generator motor. In sucha hybrid working machine, the electric energy stored in a battery to bedescribed later or the electric energy generated by the generator motoris used when accelerating (performing a power running action of) theelectric actuator, and a power generation action of the electricactuator is performed and the generated electric energy is stored in thebattery when decelerating (performing a regeneration action of) theelectric actuator. As the battery, a nickel hydride battery as aso-called secondary battery, a lithium ion battery, a capacitor, or thelike is used. For example, the capacitor may charge and discharge theelectric energy in a short time, and has a characteristic in which alarge amount of electric energy (charge) may be charged and discharged.Thus, the capacitor is mounted on the hybrid construction machine.

When performing maintenance such as a replacement of the capacitor orthe capacitor peripheral unit or an inspection of a deterioration stateof the capacitor, there is a need to perform charge extracting(discharging) of the capacitor. When discharging not only the capacitorbut also the secondary battery, the capacitor may be taken out from thehybrid working machine and the charge extracting may be performed byusing a tool such as a discharger. However, when the process ofextracting the charge of the capacitor mounted on the hybrid workingmachine may be performed by a structure in which the electric energy isconsumed (discharged) by using the engine as a load while the capacitoris provided inside the hybrid working machine or a control device (acharge/discharge device) is provided in the hybrid working machine andthe charge extracting is performed by using the charge/discharge device,there is no need to perform a troublesome work in which the dischargeris carried to the site where the hybrid working machine is operated.That is, the hybrid working machine is provided with thecharge/discharge device and power is supplied (discharged) from thecapacitor to the generator motor rotationally driven with the driving ofthe engine so as to drive the generator motor by using the operatingengine as a load, thereby performing the discharging (the chargeextracting) of the charge stored in the capacitor.

Furthermore, Patent Literature 1 discloses a configuration in which anengine as a load is driven and a current and a voltage of a generatormotor and a booster are controlled so as to promptly extract a charge ofa capacitor. Further, Patent Literature 2 discloses a configuration inwhich any one of discharging control of driving an engine starting motorby a running battery using an engine as a load and charging control ofrotationally driving the engine starting motor by the engine to chargethe running battery is performed and the IV characteristics of thebattery are calculated based on the battery current and voltage at thattime so as to inspect the battery deterioration state.

CITATION LIST Patent Literature

Patent Literature 1: WO 2008/111649 A

Patent Literature 2: JP 2000-270408 A

SUMMARY Technical Problem

Incidentally, when extracting the charge of the capacitor describedabove by using the engine as the load, the operator (an operator or aservice man) stops the engine by operating a key switch, serving as aninstruction output unit used to start or stop the engine, to an offposition so as to stop the operation of the hybrid working machinelater. As the key switch, a switch which may start or stop the engine byinserting a key into a key cylinder and rotating the key or a switchwhich may start or stop the engine by an operation of a button is used.In a case where the key switch is of a type in which the key is rotatedwhile being inserted into the key cylinder as described above, an offposition, an on position, and a start position are set in the rotationdirection. Here, the engine is stopped when the key is operated to theoff position, a current is supplied to each electric system when the keyis operated to the on position, and a starter (an engine starting motor)for starting the engine is rotationally driven so as to start the enginewhen the key is further rotated from the on position to the startposition.

However, the operator who performs the maintenance of the capacitor orthe peripheral unit thereof recognizes the completion of the chargeextracting as described above and operates the key switch to the offposition (rotates the key to the off position). Accordingly, theoperator determines that the engine is stopped and operates a monitordevice provided in an operation room of the hybrid working machine anddisplaying a machine status such as a total operation time of the hybridworking machine or a fuel remaining amount after the determination so asto check the machine status. That is, the operator may operate the keyswitch to the on position (rotate the key to the on position) so as tosupply power to the monitor device in the checking operation. At thistime, when the key is not operated (rotated) to the start position whilethe key switch is operated to the on position, the starter (the enginestarting motor) is not rotationally driven and the engine is notstarted. However, a current is supplied to a fuel injection system ofthe engine, so that a fuel is supplied into the combustion chamber ofthe engine.

Accordingly, as the key switch is operated to the off position, thesupply of the fuel from the fuel injection device to the engine isstopped and the engine speed decreases. However, since the key switch isoperated to the on position (the operation in which the key is notoperated to the start position and the starter is not rotationallydriven) while the engine speed decrease, the fuel is supplied from thefuel injection device to the engine. Then, when the engine is driven ata certain engine speed at the time point, a phenomenon occurs in whichthe fuel explodes in the combustion chamber of the engine, so that theengine speed increases. Here, the controller which controls thedistribution of the electric energy between the capacitor and thegenerator motor or between the capacitor and the other electric actuatorrecharges the capacitor as a condition in which the key switch ispresent at the on position and the engine speed transmitted from therotation sensor for detecting the engine speed exceeds the predeterminedengine speed.

That is, the predetermined engine speed indicates an engine speed whichbecomes a bifurcation used to determine whether the engine speedincreases by the fuel supplied to the engine only by the operation inwhich the key switch is operated to the on position after the key switchis operated to the off position. Even when the key switch is operated tothe on position and the fuel is supplied to the engine while the enginespeed is lower than the predetermined engine speed, the engine speeddoes not increase due to the friction resistance (the rotationresistance) of the crank shaft of the engine or the rotor shaft of thegenerator motor. That is, when the key switch is operated to the onposition while the engine speed exceeds the predetermined engine speedafter the key switch is operated to the off position, the engine speedincreases, and the generator motor mechanically coupled to the engine isrotationally driven to generate power, thereby causing a phenomenon inwhich the capacitor is recharged.

That is, even in the capacitor charge extracting completion (dischargingcompletion) state, when the engine speed is the predetermined enginespeed or more immediately after the charge extracting completion, thereis a case in which the capacitor is unexpectedly charged (recharged) bythe operator, and hence there is a problem in which the maintenance ofthe capacitor is disturbed. That is, when the capacitor subjected to thecharge extracting is recharged while being provided in the vehicle, aproblem arises when taking the capacitor out from the hybrid workingmachine to replace or check the capacitor or when performing themaintenance on the removed capacitor. When performing the inspection ofmeasuring the charge amount of the capacitor so as to check thedeterioration state of the capacitor, the discharging (chargeextracting) process needs to be essentially performed again if thecharge remains in the capacitor. Further, when discarding the capacitortaken out from the hybrid working machine, the discharging (chargeextracting) process needs to be essentially performed before theconveying operation or the disassembling operation for discarding as inthe general secondary battery if the charge remains in the capacitor.

The invention is made in view of such circumstances, and it is an objectof the invention to provide a battery charge/discharge control device, abattery charge/discharge control method, and a hybrid working machinewith a battery charge/discharge control device capable of reliablypreventing a battery from being unexpectedly charged by an operatorafter extracting a charge of the battery.

Solution to Problem

According to the present invention, a battery charge/discharge controldevice which performs battery charge/discharge control in a workingmachine with a battery capable of storing electric energy generated by agenerator motor coupled to an engine and driving the generator motor orat least one of other electric actuators by the stored electric energyand a controller which controls a distribution of the electric energyamong the battery, the generator motor, and the electric actuator,wherein the controller performs the charge/discharge control in whichthe electric energy of the battery is discharged when the engine isdriven and recharging to the battery is permitted on a condition that astate in which an engine speed is equal to or lower than a predeterminedengine speed is maintained for a predetermined time after the battery iscompletely discharged.

In the present invention, the controller performs the charge/dischargecontrol in which the recharging to the battery is prohibited until thestate in which the engine speed is equal to or lower than thepredetermined engine speed is maintained for the predetermined timeafter the battery is completely discharged.

In the present invention, the state in which the engine speed is equalto or lower than the predetermined engine speed is a state after anengine stopping instruction is generated by an instruction output unitwhich instructs starting and stopping of the engine.

In the present invention, the predetermined engine speed is an enginespeed in which the engine speed increases when an instruction outputunit which instructs starting and stopping of the engine is operated sothat a fuel injection device supplying a fuel to the engine supplies afuel to the engine after the engine is stopped by the instruction outputunit.

According to the present invention, a battery charge/discharge controldevice which performs battery charge/discharge control in a workingmachine with a battery capable of storing electric energy generated by agenerator motor coupled to an engine and driving the generator motor orat least one of other electric actuators by the stored electric energyand a controller which controls a distribution of the electric energyamong the battery, the generator motor, and the electric actuator,wherein the controller performs the charge/discharge control in whichthe electric energy of the battery is discharged when the engine isdriven and recharging to the battery is permitted on a condition that acancelation signal for canceling prohibition of recharging to thebattery is received after the battery is completely discharged.

In the present invention, the controller performs the control in whichthe recharging to the battery is prohibited until the cancelation signalfor cancelling the prohibition of the recharging to the battery isreceived after the battery is completely discharged.

In the present invention, the cancelation signal is a signal which isgenerated by an operation of an operation unit.

In the present invention, the charge/discharge control is performed bydetermining the battery discharging completion as a time point in whicha predetermined time is elapsed from a state where a voltage of thebattery is equal to or lower than a predetermined value.

According to the present invention, a battery charge/discharge controlmethod which performs battery charge/discharge control in a workingmachine with a battery capable of storing electric energy generated by agenerator motor coupled to an engine and driving the generator motor orat least one of other electric actuators by the stored electric energyand a controller which controls a distribution of the electric energyamong the battery, the generator motor, and the electric actuator,wherein the controller performs the charge/discharge control in whichthe electric energy of the battery is discharged when the engine isdriven and recharging to the battery is permitted on a condition that astate in which an engine speed is equal to or lower than a predeterminedengine speed is maintained for a predetermined time after the battery iscompletely discharged.

According to the present invention, a battery charge/discharge controlmethod which performs battery charge/discharge control in a workingmachine with a battery capable of storing electric energy generated by agenerator motor coupled to an engine and driving the generator motor orat least one of other electric actuators by the stored electric energyand a controller which controls a distribution of the electric energyamong the battery, the generator motor, and the electric actuator,wherein the controller performs the charge/discharge control in whichthe electric energy of the battery is discharged when the engine isdriven and recharging to the battery is permitted on a condition that acancelation signal for canceling prohibition of recharging to thebattery is received after the battery is completely discharged.

According to the present invention, a hybrid working machine comprises:the battery charge/discharge control device.

According to the invention, the control is performed such that theengine is stopped after performing the charge extracting process on thebattery while the battery is mounted on the hybrid working machine andthe recharging to the battery is permitted as a condition in which anystarting instruction is transmitted to the engine and the engine ismaintained at the predetermined engine speed or less for thepredetermined time or the recharging to the battery is permitted as acondition in which the cancelation signal for cancelling the prohibitionof the recharging to the battery is received after the charge of thebattery is completely extracted. Accordingly, it is possible to reliablyprevent the battery from being unexpectedly charged by the operatorafter extracting the charge of the battery.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating an entire configuration of a hybridexcavator which is an example as a working machine.

FIG. 2 is a schematic diagram including main components of the hybridexcavator and an electric circuit and a hydraulic circuit illustrating arelation between the main components.

FIG. 3 is a flowchart illustrating a sequence of a capacitorcharge/discharge control process which is performed by a capacitorcharge/discharge control unit according to a first embodiment of theinvention.

FIG. 4 is a time chart illustrating an example of the capacitorcharge/discharge control process which is performed by the capacitorcharge/discharge control unit according to the first embodiment of theinvention.

FIG. 5 is a diagram illustrating an example of a screen display of amonitor device according to the first embodiment of the invention.

FIG. 6 is a flowchart illustrating a sequence of a capacitorcharge/discharge control process which is performed by a capacitorcharge/discharge control unit according to a second embodiment of theinvention.

FIG. 7 is a time chart illustrating an example of the capacitorcharge/discharge control process which is performed by the capacitorcharge/discharge control unit according to the second embodiment of theinvention.

FIG. 8 is a diagram illustrating an example of a screen display of amonitor device according to the second embodiment of the invention.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of the invention will be described byreferring to the accompanying drawings.

First Embodiment

First, FIGS. 1 and 2 illustrate an entire configuration of a hybridexcavator 1 which is an example as a hybrid working machine.Furthermore, a concept of a simple working machine instead of a hybridtype includes a construction machine such as an excavator, a bulldozer,a dump truck, and a wheel loader, and the construction machine with apeculiar hybrid characteristic configuration is set as a hybrid workingmachine. The hybrid excavator 1 includes a vehicle body 2 and a workingunit 3. The vehicle body 2 includes a lower running body 4 and an upperswing body 5. The lower running body 4 includes a pair of runningdevices 4 a. Each running device 4 a includes a crawler track 4 b. Eachrunning device 4 a drives the crawler track 4 b by the rotationaldriving of a right running hydraulic motor 34 and a left runninghydraulic motor 35 illustrated in FIG. 2 so that the hybrid excavator 1runs.

The upper swing body 5 is provided in the upper portion of the lowerrunning body 4 so as to be swingable, a swing motor 23 is connected to adriving shaft of a swing machinery 24 (decelerator), a rotational forceof the swing motor 23 is transmitted through the swing machinery 24, andthe transmitted rotational force is transmitted to the upper swing body5 through a swing pinion and a swing circle (not illustrated) so as toswing the upper swing body 5. Further, the upper swing body 5 isprovided with an operation room 6. The upper swing body 5 includes afuel tank 7, a hydraulic oil tank 8, an engine room 9, and a counterweight 10. The fuel tank 7 stores fuel for driving an engine 17. Thehydraulic oil tank 8 stores hydraulic oil discharged from a hydraulicpump 18 with respect to hydraulic units which are a hydraulic cylindersuch as a boom hydraulic cylinder 14, an arm hydraulic cylinder 15, anda bucket hydraulic cylinder 16 and a hydraulic motor (a hydraulicactuator) such as the right running hydraulic motor 34 and the leftrunning hydraulic motor 35. The engine room 9 accommodates various unitssuch as the engine 17, the hydraulic pump 18, a generator motor 19, anda capacitor 25. The counter weight 10 is disposed behind the engine room9.

The working unit 3 is attached to the center position of the frontportion of the upper swing body 5, and includes a boom 11, an arm 12, abucket 13, the boom hydraulic cylinder 14, the arm hydraulic cylinder15, and the bucket hydraulic cylinder 16. The base end of the boom 11 isconnected to the upper swing body 5 so as to be swingable. Further, thefront end which is opposite to the base end of the boom 11 is connectedto the base end of the arm 12 so as to be rotatable. The bucket 13 isconnected to the front end which is opposite to the base end of the arm12 so as to be rotatable. Further, the bucket 13 is connected to thebucket hydraulic cylinder 16 through a link. The boom hydraulic cylinder14, the arm hydraulic cylinder 15, and the bucket hydraulic cylinder 16are hydraulic cylinders (hydraulic actuators) which are operated in atelescopic manner by the hydraulic oil discharged from the hydraulicpump 18. The boom hydraulic cylinder 14 swings the boom 11. The armhydraulic, cylinder 15 swings the arm 12. The bucket hydraulic cylinder16 swings the bucket 13.

In FIG. 2, the hybrid excavator 1 includes the engine 17, the hydraulicpump 18, and the generator motor 19 as driving sources. A diesel engineis used as the engine 17, and a variable displacement hydraulic pump isused as the hydraulic pump 18. For example, a swash plate type hydraulicpump which changes the pump capacity by changing the tilting angle ofthe swash plate 18 a is used. The engine 17 is provided with a rotationsensor 41 which detects an engine speed, and a signal which representsthe engine speed detected by the rotation sensor 41 is input to a hybridcontroller C2. The rotation sensor 41 is operated by receiving powerfrom a battery (not illustrated), and detects the engine speed of theengine 17 as long as a key switch 31 to be described later is operatedto an on (ON) or start (ST) position. The hydraulic pump 18 and thegenerator motor 19 are mechanically coupled to a driving shaft 20 of theengine 17, and when the engine 17 is driven, the hydraulic pump 18 andthe generator motor 19 are driven. As a hydraulic driving system, thehydraulic driving system includes an operation valve 33, the boomhydraulic cylinder 14, the arm hydraulic cylinder 15, the buckethydraulic cylinder 16, the right running hydraulic motor 34, and theleft running hydraulic motor 35, and such hydraulic units are driven byusing the hydraulic pump 18 as a hydraulic oil supply source to thehydraulic driving system. Furthermore, the operation valve 33 is a flowdirection control valve, where a spool (not illustrated) is moved inresponse to the operation direction of each operation lever 32 so as toregulate the hydraulic oil flow direction to each hydraulic actuator andto supply the hydraulic oil in response to the operation amount of theoperation lever 32 to the hydraulic actuator such as the boom hydrauliccylinder 14, the arm hydraulic cylinder 15, the bucket hydrauliccylinder 16, the right running hydraulic motor 34, or the left runninghydraulic motor 35.

An electric driving system includes a driver 21 which is connected tothe generator motor 19 through a power cable, an inverter 22 which isconnected to the driver 21 through a wiring harness, a booster 26 whichis provided between the driver 21 and the inverter 22 through a wiringharness, a capacitor 25 which is connected to the booster 26 through acontactor 27 (an electromagnetic contactor), a swing motor 23 which isconnected to the inverter 22 through a power cable, and the like.

Furthermore, the contactor 27 generally closes the electric circuitbetween the capacitor 25 and the booster 26 so as to become a powerdistribution state. Meanwhile, when the hybrid controller C2 determinesthat the electric circuit needs to be opened due to detection of theleakage of electricity or the like, the hybrid controller C2 outputs aninstruction signal for changing the power distribution state to thecontactor 27 to the interruption state. Then, the contactor 27 whichreceives the instruction signal from the hybrid controller C2 opens theelectric circuit.

The swing motor 23 is mechanically connected to the swing machinery 24as described above. The electric energy which is generated by thegenerator motor 19 or the electric energy which is stored in thecapacitor 25 becomes a power source of the swing motor 23, and swingsthe upper swing body 5 through the swing machinery 24. That is, theswing motor 23 swings and accelerates the upper swing body 5 byperforming a power running action using the electric energy suppliedfrom the generator motor 19 or the capacitor 25. Then, when the upperswing body 5 swings in an deceleration state, the swing motor 23performs a regeneration action, and the electric energy which isgenerated by the regeneration action is supplied (charged) to thecapacitor 25.

Further, the generator motor 19 supplies (charges) the generatedelectric energy to the capacitor 25, and supplies the electric energy tothe swing motor 23 depending on the status. As the generator motor 19,for example, a SR (switched reluctance) motor is used. Furthermore, evenwhen a synchronous electric motor using a permanent magnet is usedinstead of the SR motor, it is possible to supply the electric energy tothe capacitor 25 or the swing motor 23. However, in a case where the SRmotor is used, the SR motor is advantageous from the viewpoint of thecost since the motor does not use a magnet including expensive raremetal. The generator motor 19 is mechanically coupled to the drivingshaft 20 of the engine 17. Accordingly, the rotor shaft of the generatormotor 19 is rotated by the driving of the engine 17.

The booster 26 raises the voltage of the electric energy (the chargestored in the capacitor 25) supplied to the generator motor 19 or theswing motor 23 through the driver 21 and the inverter 22. The raisedvoltage is applied to the generator motor 19 when assisting the power ofthe swing motor 23 or the engine 17. Furthermore, the booster 26 is alsoused to drop the voltage when charging the electric energy generated bythe generator motor 19 or the swing motor 23 to the capacitor 25.

Furthermore, the respective torques of the generator motor 19 and theswing motor 23 are controlled by the driver 21 and the inverter 22 underthe control by the hybrid controller C2. In the amount (the chargeamount or the capacitance) of the electric energy stored in thecapacitor 25, the magnitude of the voltage may be managed as an index.In order to detect the magnitude of the voltage, a predetermined outputterminal of the capacitor 25 is provided with a voltage sensor 28. Thevoltage which is detected by the voltage sensor 28 is transmitted as anelectric signal to the hybrid controller C2. Then, the hybrid controllerC2 monitors the charged amount (the amount of the electric energy (thecharge amount or the capacitance)) of the capacitor 25, and performs amanagement in which the electric energy generated by the generator motor19 is supplied (charged) to the capacitor 25 or is supplied to the swingmotor 23 (where the power is supplied for the power running action).

Further, for example, an electric double layer capacitor is used as thecapacitor 25. Instead of the capacitor 25, a battery which serves asanother secondary battery such as a lithium-ion battery or a nickelhydride battery may be used. Further, as the swing motor 23, forexample, a permanent magnet type synchronous electric motor is used.

The hydraulic driving system and the electric driving system are drivenin response to the operation of the operation levers 32 such as aworking unit lever, a running lever, and a swing lever which areinstalled inside the operation room 6 provided inside the vehicle body2. In a case where the operator of the hybrid excavator 1 operates theoperation lever 32 (the swing lever) serving as an operation unit forswinging the upper swing body 5, the operation direction and theoperation amount of the swing lever are detected by a potentiometer or apilot pressure sensor, and the detected operation amount is transmittedas an electric signal to the controller C1 and the hybrid controller C2.Even when the other operation lever 32 is operated, the electric signalis transmitted to the respective controllers in this way. In response tothe operation direction and the operation amount of the swing lever orthe operation direction and the operation amount of the other operationlever 32, the controller C1 and the hybrid controller C2 control theinverter 22, the booster 26, or the driver 21 so as to perform therotation operation (the power running action or the regeneration action)of the swing motor 23 or the power distribution control (the energymanagement) such as the management (the control for charging ordischarging) of the electric energy of the capacitor 25 and themanagement (the assist for the generation or the engine output and thepower running action to the swing motor 23) of the electric energy ofthe generator motor 19.

A monitor device 30 and a key switch 31 are installed inside theoperation room 6 in addition to the operation lever 32. The monitordevice 30 includes a liquid crystal panel, an operation button, and thelike. Further, the monitor device 30 may be a touch panel obtained byintegrating the display function of the liquid crystal panel with thefunction of the operation button for inputting various informationitems. The monitor device 30 is an information input and output devicewhich has a function of informing the operator or the service man ofinformation representing the operation state (the engine watertemperature state, the failure state of the hydraulic unit, or the fuelremaining amount) of the hybrid excavator 1 and a function of performingthe setting or the instruction (the setting of the output level of theengine, the setting of the speed level of the running speed, or thecapacitor charge extracting instruction) desired by the operator withrespect to the hybrid excavator 1.

The key switch 31 mainly includes a key cylinder as a constitutingcomponent. The key is inserted into the key cylinder and generates aninstruction of driving the engine (the starting of the engine) in amanner such that the key is rotated so as to start the starter (theengine starting motor) provided in the engine 17 or generates aninstruction of stopping the engine (the stopping of the engine) in amanner such that the key is rotated in the direction opposite to thecase of starting the engine in the engine driving state. That is, thekey switch 31 is an instruction output unit which outputs an instructionto various electric units of the engine 17 or the hybrid working machine1. When the key is rotated (specifically, the key is operated to the offposition to be described later) in order to stop the engine, the supply(feeding) of the electricity to various electric units from the battery(not illustrated) or the supply of fuel to the engine 17 is interrupted,so that the engine is stopped. As illustrated in FIG. 2, The key switch31 interrupts the feeding of electricity to various electric units fromthe battery (not illustrated) when the key is rotated to the off (OFF)position, and feeds the electricity to various electric units from thebattery (not illustrated) when the key is operated to the on (ON)position. Then, when the key is further rotated from that position tothe start (ST) position, the starter (not illustrated) is startedthrough the controller C1, thereby starting the engine. The key rotationposition is present at the on (ON) position while the engine is drivenafter the engine 17 is started.

Furthermore, instead of the key switch 31 which mainly includes the keycylinder described above, another instruction output unit, for example,a press button type key switch may be employed. That is, the key switchmay be configured so that the engine becomes an on (ON) state when abutton is pressed once while the engine is stopped, the engine becomesan start (ST) state when the button is pressed further, and the enginebecomes an off (OFF) state when the button is pressed while the engineis driven. Further, the key switch may be configured to start the engineas the condition in which the button is continuously pressed during apredetermined time while the engine is stopped so that the engine stateis switched from the off (OFF) state to the start (ST) state.

The controller C1 includes a calculation device such as a CPU (anumerical calculation processor) or a memory (a storage device). Thecontroller C1 controls the engine 17 and the hydraulic pump 18 based onthe instruction signal output from the monitor device 30, theinstruction signal output in response to the key position of the keyswitch 31, and the instruction signal (the signal representing theoperation amount or the operation direction described above) output inresponse to the operation of the operation lever 32. The engine 17 is anengine in which electronic control may be performed by a common railtype fuel injection device 40. The engine may obtain a target engineoutput by appropriately controlling the fuel injection amount using thecontroller C1, and may set the engine speed and the output torque inresponse to the load state of the hybrid excavator 1.

The hybrid controller C2 controls the driver 21, the inverter 22, andthe booster 26 as described above under the cooperation control with thecontroller C1, and controls the distribution of the electric energy ofthe generator motor 19, the swing motor 23, and the capacitor 25. Thehybrid controller C2 includes a capacitor charge/discharge control unitC21. During the maintenance of the capacitor 25 or the peripheral unitthereof, the capacitor charge/discharge control unit C21 performs acontrol program for the capacitor charge/discharge control process to bedescribed later.

Here, a capacitor charge/discharge control process which is performed bythe capacitor charge/discharge control unit C21 of the first embodimentwill be described by referring to the flowchart illustrated in FIG. 3.The capacitor charge/discharge control process is started while theengine 17 is driven. As will be described later, the engine 17 is drivensince the electric energy stored in the capacitor 25 is consumed(discharged) by using the engine 17 as a load. As illustrated in FIG. 3,the capacitor charge/discharge control unit C21 first determines whetherthere is a charge extracting instruction (step S101). The chargeextracting instruction is an instruction signal which is generated bythe operation of a predetermined operation button installed in themonitor device 30 from an operator or a service man (hereinafter,generally referred to as an operator), and the instruction signal isinput to the capacitor charge/discharge control unit C21 through thecontroller C1. Specifically, the operator who performs the maintenanceof the capacitor 25 or the peripheral unit thereof operates theoperation button disposed on the monitor screen of the monitor device 30or the operation button disposed in the monitor device 30 or thevicinity thereof while the engine 17 is driven, inputs a specificpassword or the like, and changes the monitor screen (a normal screendisplaying the engine water temperature or the fuel remaining amount) tothe maintenance screen. Subsequently, in order to select the capacitorcharge extracting item from the maintenance screen, a portion indicatingthe capacitor charge extracting item displayed on the monitor screen ispressed by a finger in a case where the monitor device 30 is a touchpanel or the operation button provided in the monitor device 30 or theoperation button disposed near the monitor device 30 is operated in acase where the monitor device 30 is not a touch panel. Then, aninstruction signal which instructs the charge extracting is generated,and the instruction signal is transmitted to the controller C1.

When there is the charge extracting instruction (Yes in step S101), thecapacitor charge/discharge control unit C21 becomes a discharging mode(step S102), causes a current to flow from the capacitor 25 to thebooster 26 while turning on the contactor 27, controls the booster 26and the driver 21 so that the generator motor 19 is driven so as toconsume (discharge) the electric energy stored in the capacitor 25 bythe generator motor 19, and performs the charge extracting of thecapacitor 25 by using the engine 17 as a load. Subsequently, thecapacitor charge/discharge control unit C21 determines whether thecharge extracting is completed (step S103). The determination in stepS103 will be described. The capacitor voltage of the capacitor 25 issequentially detected by the voltage sensor 28, a signal whichrepresents the capacitor voltage detected by the voltage sensor 28 isreceived by the hybrid controller C2, and the capacitor charge/dischargecontrol unit C21 determines that the charge extracting is completed whenthe capacitor voltage is lower than a predetermined value Vth for apredetermined time ΔT1.

Then, when the charge extracting is completed (Yes in step S103), thecharge extracting completion (discharging completion) mode is selected(step S104). The charge extracting completion mode is a mode in whichthe recharging to the capacitor 25 is prohibited. That is, in the chargeextracting completion mode, even when the key switch 31 is operated tothe on position or the start position after the key switch 31 is firstoperated to the off position, the capacitor charge/discharge controlunit C21 generates an interlock control signal (a recharging prohibitionsignal) of preventing the charging of the electric energy generated bythe generator motor 19 to the capacitor 25, and outputs and maintainsthe recharging prohibition signal to the driver 21 or the inverter 22.

Furthermore, when the charge extracting is completed, as illustrated inFIG. 5, a display representing the completion of the charge extractingand a display of changing the key switch 31 to the off (OFF) state aredisplayed on the monitor screen W1 of the monitor device 30. Then, whenthe key switch 31 is operated to the off position, the fuel injectiondevice 40 stops the supply of the fuel to the engine 17, so that theengine speed decreases. Furthermore, as illustrated in FIG. 5, thecapacitor charging rate is displayed as a numerical value on the monitorscreen W1 based on the capacitor voltage which is detected by thevoltage sensor 28. The capacitor charging rate is set as 100% in thefull charged state and is set as 0% when the capacitor voltage is equalto or lower than a predetermined value Vth, where the amount of theelectric energy stored in the capacitor 25 is indicated by the numericalvalue in percentage. With such a numerical display, the operator mayrecognize the charging state of the capacitor 25.

Subsequently, the capacitor charge/discharge control unit C21 determineswhether the engine speed is maintained at a predetermined value Nth1 orless for a predetermined time ΔT2 (step S105). When the engine speeddetected by the rotation sensor 41 is maintained at the predeterminedvalue Nth1 or less for the predetermined time ΔT2 (Yes in step S105),the recharging permission mode is selected (step S106). The rechargingpermission mode is a mode in which the recharging to the capacitor 25 ispermitted. Here, the relation between the predetermined value Nth1 andthe operation states of the key switch 31 and the engine 17 will bedescribed below. After the key switch 31 is operated to the off (OFF)position, the key switch 31 is operated to the on (ON) position whilethe engine 17 is driven so that the engine speed exceeds thepredetermined value Nth1. However, in a state where the starter (notillustrated) is not started (that is, the key switch 31 is not rotatedto the start (ST) position), the fuel injection device 40 supplies thefuel to the combustion chamber of the engine 17. The fuel injectiondevice 40 supplies the fuel into the combustion chamber of the engine 17with the operation of the key switch 31 to the on (ON) position. In thisstate, the engine 17 does not receive the instruction signal of theengine output (the target engine speed or the target torque) from thecontroller C1 since the engine is not continuously driven in general.However, the combustion of the fuel occurs in the combustion chamber byreceiving the fuel while the engine 17 rotates at the engine speed equalto or higher than the predetermined value Nth1. As a result, the engine17 does not receive the instruction signal from the controller C1, but aphenomenon occurs in which the engine speed independently increases.When the engine speed is lower than the predetermined value Nth1, theengine speed does not increase independently due to a load such as arotation resistance of a crank shaft or a rotation resistance of a rotorshaft of the generator motor 19 even when the fuel is supplied to theengine 17. Accordingly, the predetermined value Nth1 is different due tothe type or the structure of the engine 17 or the generator motor 19,and is obtained based on the original characteristics of the engine 17and the like. However, the predetermined value is the engine speed usedas the bifurcation for determining whether the engine speed increaseswhen the key switch 31 is operated to the on (ON) position after theengine is stopped as described above. Accordingly, when the engine speedis equal to or lower than the predetermined value Nth1, the engine speedof the engine 17 does not increase independently even when the keyswitch 31 is operated to the on (ON) position.

Subsequently, the capacitor charge/discharge control unit C21 determineswhether the charging start condition is satisfied (step S107). Thecharging start condition is a condition in which the key switch 31 isoperated to the on (ON) or start (ST) position and the engine speed isequal to or higher than a predetermined value Nth2 on the assumption ofthe recharging permission mode. Furthermore, the predetermined valueNth2 is set to a value larger than the predetermined value Nth1, and thetwo set values are values smaller than the engine speed Ni in which theidling state is maintained. When the charging start condition issatisfied (Yes in step S107) in the recharging permission mode, therecharging to the capacitor 25 is started (step S108). That is, thecapacitor charge/discharge control unit C21 controls the driver 21 andperforms a process in which the electric energy (the charge) generatedby the generator motor 19 is stored (charged) to the capacitor 25through the booster 26. Subsequently, the routine proceeds to step S101so as to repeat the above-described process. Furthermore, when anegative determination is made in step S101, step S103, step S105, andstep S107, the determination process in each of step S101, S103, S105,and S107 is repeated.

Here, the specific capacitor charge/discharge control process accordingto the first embodiment will be described by referring to the time chartillustrated in FIG. 4. In time chart illustrated in FIG. 4( a), thehorizontal axis indicates the time, and the vertical axis indicates achange in the capacitor voltage (V). In the time chart illustrated inFIG. 4( b), the horizontal axis indicates the time, and the verticalaxis indicates a change in the engine speed (N). In the time chartillustrated in FIG. 4( c), the horizontal axis indicates the time, andthe vertical axis indicates a change in the position in which the keyswitch 31 is operated. In the time chart illustrated in FIG. 4( d), thehorizontal axis indicates the time, and a change in the mode of thecapacitor charge/discharge control device C21 is illustrated.

As illustrated in FIG. 4, when there is an instruction of extracting thecharge of the capacitor 25 at the time point t1, the capacitorcharge/discharge control device C21 becomes a discharging mode, controlsthe engine speed N by the controller C1 and the hybrid controller C2 ata predetermined value Ni (for example, 800 rpm) in which the engine 17is maintained in an idling state, and starts and performs the chargeextracting by using the engine 17 as a load. Furthermore, thepredetermined value Ni may be set to the other engine speed instead ofthe engine speed which is defined as the idling state. While the chargeextracting is performed (in the discharging mode), the capacitor voltagegradually decreases and reaches the capacitor voltage (a predeterminedvalue Vth (which is a predetermined voltage, for example, 10 V)) inwhich the charging of the capacitor 25 is substantially completed. Thecapacitor charge/discharge control unit C21 determines that the chargeextracting is completed at the time point t3 in which the state of thepredetermined value Vth or less is maintained for a predetermined timeΔT1 (for example, 10 minutes) from the time point t2 in which thecapacitor voltage becomes the predetermined value Vth, and changes themode from the discharging mode to the charge extracting completion mode.When the charge extracting completion mode is selected, the controllerC1 receives a signal for representing the selection of the chargeextracting completion mode from the hybrid controller C2. Then, thecontroller C1 outputs a control signal to the monitor device 30 so as todisplay the “guide for notifying the completion of the charge extractingand the switching of the key switch to the off state and the capacitorcharging rate on the monitor screen W1” (hereinafter, such a display isreferred to as the display of the guide for the charge extractingcompletion) as illustrated in FIG. 5.

The operator operates the key switch 31 to the off position at the timepoint t4 in accordance with the display of the guide for the chargeextracting completion, so that the engine speed gradually decreases fromthe idling state (the engine speed Ni). Since the fuel supplyinstruction signal which is output from the controller C1 to the fuelinjection device 40 is interrupted in the engine driving state with theoperation of the key switch 31 to the off position, the engine speeddecreases. However, the engine speed does not become zero until theinertial force disappears. The time is elapsed to the time point t5, andthe time reaches a bifurcation used to determine whether the engine 17is independently rotated as described above. Then, the engine speeddecreases to the predetermined value Nth1 (for example, 300 rpm). Whenthe engine speed N is equal to or lower than the predetermined valueNth1 for a predetermined time ΔT2 (for example, 1 second) from the timepoint t5, it is considered that the engine 17 is completely stopped (theengine stop state). Even when the key switch 31 is operated to the onposition in the engine stop state, the engine speed does not reach thepredetermined value Nth2 or more, and the recharging to the capacitor 25is not performed. Subsequently, the capacitor charge/discharge controlunit C21 is changed from the charge extracting completion mode to therecharging permission mode at the time point t6 in which the time iselapsed by the predetermined time ΔT2. That is, the rechargingpermission mode is a mode in which the recharging to the capacitor 25 ispermitted and the recharging prohibition signal which has been output iscanceled.

When the key switch 31 is operated from the off position to the onposition at the time point (for example, the time point t7) in which therecharging permission mode is effective and the key switch is furtherrotated to the start position, the starter is actuated at the time pointt8 and the engine 17 is started. After the key switch 31 is operated tothe start (ST) position as described above, the key switch is maintainedat the on (ON) position and the driving of the engine 17 is continued sothat the engine speed N increases. When the engine speed N reaches thepredetermined value Nth2 (for example, 500 rpm) at the time point t9after the engine 17 is started, the capacitor charge/discharge controlunit C21 determines that the charging start condition is established andcontrols the driver 21, the booster 26, and the inverter 22 so as torecharge the electric energy generated by the generator motor 19 to thecapacitor 25. As a result, the capacitor voltage V gradually increases.In this way, the action in which the key switch 31 is operated to the onposition and is further operated to the start position so as to startthe starter is the operator's intention to perform the recharging, andthe control of charge/discharge the capacitor 25 is performed so thatthe operator's intention matches the control content.

In the first embodiment, the control (in which the rechargingprohibition signal is generated and the output of the rechargingprohibition signal is maintained) of not permitting the recharging tothe capacitor 25 is performed as the charge extracting completion modeuntil the engine speed is maintained for the predetermined time ΔT2 atthe engine speed (the predetermined value Nth1) or less as a bifurcationused to determine whether the engine 17 is rotationally drivenindependently due to the original characteristics of the engine 17 andthe like from the charge extracting completion (the time point t3illustrated in FIG. 4 and the charging completion) of the capacitor 25,and the control of permitting the recharging to the capacitor 25 isperformed by selecting the recharging permission mode as the conditionin which the engine speed is maintained at the predetermined value Nth1or less for the predetermined time ΔT2 after the charge extractingcompletion of the capacitor 25. According to the batterycharge/discharge control device, the battery charge/discharge controlmethod, and the hybrid working machine with the battery charge/dischargecontrol device, it is possible to reliably prevent the charging of thecapacitor 25 from being unexpectedly performed by the operator after thecharge extracting completion of the capacitor 25.

Second Embodiment

Next, a second embodiment of the invention will be described. In thebattery charge/discharge control device, the battery charge/dischargecontrol method, and the hybrid working machine with the batterycharge/discharge control device of the first embodiment, the control ofprohibiting the recharging to the capacitor 25 is performed as thecharge extracting completion (discharging completion) mode until theengine speed is maintained for the predetermined time ΔT2 at thepredetermined engine speed (the predetermined value Nth1) or less as abifurcation used to determine whether the engine 17 is independentlydriven due to the original characteristics of the engine 17 and thelike, and the recharging permission mode is selected so as to permit therecharging. In the second embodiment, the time point in which the chargeextracting completion mode is switched to the recharging permission modeby the capacitor recharging control unit C21 is set as the time point inwhich the cancelation signal of instructing the cancelation of thecharge extracting completion mode is received.

FIG. 6 is a flowchart illustrating the sequence of the capacitorcharge/discharge control process which is performed by the capacitorcharge/discharge control unit C21 according to the second embodiment ofthe invention. As illustrated in FIG. 6, in step S201 to S204, thecharge extracting completion mode is first selected after the chargeextracting completion as in step S101 to S104. Furthermore, in thecharge extracting completion mode, the key switch 31 may not beessentially operated to the off position, and the engine speed may be inthe idling state. Further, at the time point in which the chargeextracting completion mode is selected, the monitor screen W2illustrated in FIG. 8 is displayed on the screen of the monitor device30 so as to notify the charge extracting completion mode throughletters, and a cancelation button SW is displayed as an icon so as tocancel the charge extracting completion mode and select the rechargingpermission mode.

Subsequently, the capacitor charge/discharge control unit C21 determineswhether the cancelation signal which is generated with the pressing ofthe operation button (the icon indicating the cancelation button SW inthe case where the monitor device 30 is the touch panel) correspondingto the cancelation button SW displayed inside the monitor screen W2illustrated in FIG. 8 is received (step S205). When the capacitorcharge/discharge control unit C21 receives the cancelation signal (Yesin step S205), the mode is changed to the recharging permission mode(step S206). The recharging permission mode is a mode in which therecharging to the capacitor 25 is permitted.

Subsequently, it is determined whether the charging start condition issatisfied (step S207). The charging start condition is a condition inwhich the key switch 31 is at the on or start position and the enginespeed is equal to or higher than the predetermined value Nth2 on theassumption that the mode is the recharging permission mode. When thecharging start condition is satisfied (Yes in step S207) in therecharging permission mode, the recharging to the capacitor 25 by thegeneration of the generator motor 19 is started (step S208). That is,the capacitor charge/discharge control unit C21 controls the driver 21or the inverter 22 and performs a process in which the electric energy(the charge) generated by the generator motor 19 is accumulated(charged) to the capacitor 25 through the booster 26. Subsequently, theroutine proceeds to step S201 so as to repeat the above-describedprocess depending on the necessity later. Furthermore, when a negativedetermination is made in step S201, step S203, step S205, and step S207,the determination process in each of step S201, S203, S205, and S207 isrepeated.

Here, the specific capacitor charge/discharge control process accordingto the second embodiment will be described by referring to the timechart illustrated in FIG. 7. In the time chart illustrated in FIG. 7(a), the horizontal axis indicates the time, and the vertical axisindicates a change in the capacitor voltage (V). In the time chartillustrated in FIG. 7( b), the horizontal axis indicates the time, andthe vertical axis indicates a change in the engine speed (N). In thetime chart illustrated in FIG. 7( c), the horizontal axis indicates thetime, and the vertical axis indicates a change in the position in whichthe key switch 31 is operated. In the time chart illustrated in FIG. 7(d), the horizontal axis indicates the time, and the vertical axisindicates a change in the output (on or off) of the cancelation signal.In the time chart illustrated in FIG. 7( e), the horizontal axisindicates the time, and a change in the mode of the capacitorcharge/discharge control unit C21 is illustrated.

As illustrated in FIG. 7, when there is an instruction of extracting thecharge of the capacitor 25 at the time point t1, the capacitorcharge/discharge control unit C21 selects the discharging mode. Then,the engine speed N of the engine 17 is controlled at the predeterminedvalue Ni (for example, 800 rpm) corresponding to the idling state by thecontroller C1, and the charge extracting is performed by using theengine 17 as a load. Subsequently, the capacitor charge/dischargecontrol unit C21 determines that the charge extracting is completed atthe time point′ t3 in which the state of the predetermined value Vth orless is maintained for the predetermined time ΔT1 (for example, 10minutes) from the time point t2 in which the capacitor voltage Vgradually decreases and becomes the capacitor voltage (the predeterminedvalue Vth (for example, 10 V) as the predetermined voltage)corresponding to the level where the discharging of the capacitorvoltage is substantially completed. Then, the capacitor charge/dischargecontrol unit C21 changes the mode from the discharging mode to thecharge extracting completion mode. When the charge extracting completionmode is selected, the monitor screen W2 displays the completion of thecharge extracting and the icon indicating the cancelation button SW (seeFIG. 8). In a case where the monitor device 30 is the touch panel, thecharge extracting completion mode is maintained and the recharging isprohibited as long as the icon (the operation unit) indicating thecancelation button SW is not pressed. In a case where there is theoperation button (the operation unit) provided in the monitor device 30or the operation button (the operation unit) disposed near the monitordevice 30 and the operation button corresponding to the cancelationbutton SW is provided, the charge extracting completion mode ismaintained and the recharging is prohibited as long as the operationbutton corresponding to the cancelation button SW is not pressed.

When the operator presses the cancelation button SW, a pressing signalis generated (a cancelation signal becomes an ON state), the pressingsignal is transmitted to the capacitor charge/discharge control unit C21through the controller C1. As a result, the capacitor charge/dischargecontrol unit C21 changes the mode from the charge extracting completionmode to the recharging permission mode at the time point t13 in whichthe cancelation button is pressed. That is, the mode is changed to themode in which the recharging to the capacitor 25 is permitted. Asillustrated in FIG. 7, the key switch 31 is operated to the off positionat the time point t11, and the engine speed slightly decreases from Ni.Then, the key switch 31 is operated to the on position, and the engine17 receives the fuel from the fuel injection device 40. When the enginespeed N increases and the engine speed N becomes equal to or higher thanNth2 (the engine is independently driven), this state is considered asthe current state. In such a state, since the engine speed is equal toor higher than the predetermined value Nth2 and the key switch 31 ispresent at the on position at the time point t13 in which the capacitorcharge/discharge control unit C21 receives the cancelation signal andchanges the mode to the recharging permission mode with the elapsing ofthe time, the charging start condition is satisfied (a positivedetermination in step S207 of FIG. 6), the recharging is immediatelystarted, and the capacitor voltage V gradually increases. The operator'soperation in which the cancelation button SW is pressed is theoperator's intention in which the recharging is performed, and thecontrol of charge/discharge the capacitor 25 is performed so that theoperator's intention matches the control content.

As illustrated in FIG. 7, even when the key switch 31 is operated to theoff position at the time point t11 in which the mode is the chargeextracting completion mode and the key switch 31 is operated to the onposition at the time point t12, the recharging to the capacitor 25 isnot performed since the mode is not the recharging permission mode. Thesame applies to the temporary blackout which is generated regardless ofthe operation of the key switch 31 and is similar to the short intervalbetween the time points t11 and t12, that is, the key switch 31 iselectrically changed from the on state to the off state and is returnedto the on state.

In the second embodiment, the control of prohibiting the recharging tothe capacitor 25 is performed until the capacitor charge/dischargecontrol unit C21 receives the cancelation signal of cancelling theprohibition of the recharging to the capacitor 25 with the pressing ofthe cancelation button SW from the charge extracting completion (thedischarging completion) of the capacitor 25, and the control ofpermitting the recharging to the capacitor 25 by the generator motor 19is performed by selecting the recharging permission mode as thecondition in which the capacitor charge/discharge control unit C21receives the cancelation signal of canceling the prohibition of therecharging to the capacitor 25 after the charge extracting completion ofthe capacitor 25. Accordingly, it is possible to reliably prevent thecapacitor 25 from being unexpectedly charged by the operator after thecharge extracting of the capacitor 25.

Furthermore, in the above-described second embodiment, a case has beendescribed in which the operation unit such as the icon or the operationbutton of the cancelation button SW is provided on the monitor screen asthe unit that generates the cancelation signal, but the invention is notlimited thereto. That is, the other operation unit may be also employed.For example, as the generation of the cancelation signal, an operationlever signal which is generated by the operation of the specificoperation lever 32, an on signal of an engine stop switch which isprovided at the lower portion of the driver seat separately from the keyswitch 31 so as to stop the engine 17, or a wireless signal which isinput from the outside of the hybrid excavator 1 through a receivingdevice provided in the hybrid excavator 1 may be employed.

Furthermore, in the above-described first or second embodiment, anexample has been described in which the battery charge/discharge controldevice or the battery charge/discharge control method is applied to thehybrid excavator, but the device and the method may be also applied tothe other construction machine. For example, bulldozer, a wheel loader,or the like provided in a running mechanism may employ the system inwhich the generator motor is driven by the engine, the electric energygenerated by the generator motor is stored in the battery such as acapacitor or a lithium ion battery, and the motor is rotationally drivenby receiving the electric energy from the battery. Even in theconstruction machine, there is a need to reliably perform the chargeextracting (the discharging) of the battery when inspecting, repairing,and replacing the battery and to reliably prevent the unexpectedcharging by the operator.

REFERENCE SIGNS LIST

-   -   1 hybrid excavator    -   2 vehicle body    -   3 working machine    -   4 lower running body    -   5 upper swing body    -   11 boom    -   12 arm    -   13 bucket    -   14 boom hydraulic cylinder    -   15 arm hydraulic cylinder    -   16 bucket hydraulic cylinder    -   17 engine    -   18 hydraulic pump    -   18 a swash plate    -   19 generator motor    -   20 driving shaft    -   21 driver    -   22 inverter    -   23 swing motor    -   24 swing machinery    -   25 capacitor    -   26 booster    -   27 contactor    -   28 voltage sensor    -   30 monitor device    -   31 key switch    -   32 operation lever    -   34 right running hydraulic motor    -   35 left running hydraulic motor    -   40 fuel injection device    -   41 rotation sensor    -   C1 controller    -   C2 hybrid controller    -   C21 capacitor charge/discharge control unit

1-4. (canceled)
 5. A battery charge/discharge control device whichperforms battery charge/discharge control in a working machine with abattery capable of storing electric energy generated by a generatormotor coupled to an engine and driving the generator motor or at leastone of other electric actuators by the stored electric energy and acontroller which controls a distribution of the electric energy amongthe battery, the generator motor, and the electric actuator, wherein thecontroller performs the charge/discharge control in which the electricenergy of the battery is discharged when the engine is driven andrecharging to the battery is permitted on a condition that a cancelationsignal for canceling prohibition of recharging to the battery isreceived after the battery is completely discharged.
 6. The batterycharge/discharge control device according to claim 5, wherein thecontroller performs the control in which the recharging to the batteryis prohibited until the cancelation signal for cancelling theprohibition of the recharging to the battery is received after thebattery is completely discharged.
 7. The battery charge/dischargecontrol device according to claim 5, wherein the cancelation signal is asignal which is generated by an operation of an operation unit. 8-9.(canceled)
 10. A battery charge/discharge control method which performsbattery charge/discharge control in a working machine with a batterycapable of storing electric energy generated by a generator motorcoupled to an engine and driving the generator motor or at least one ofother electric actuators by the stored electric energy and a controllerwhich controls a distribution of the electric energy among the battery,the generator motor, and the electric actuator, the method comprising:performing, by the controller, the charge/discharge control in which theelectric energy of the battery is discharged when the engine is drivenand recharging to the battery is permitted on a condition that acancelation signal for canceling prohibition of recharging to thebattery is received after the battery is completely discharged. 11.(canceled)
 12. The battery charge/discharge control device according toclaim 5, wherein the charge/discharge control is performed bydetermining the battery discharging completion as a time point in whicha predetermined time is elapsed from a state where a voltage of thebattery is equal to or lower than a predetermined value.
 13. A hybridworking machine comprising: the battery charge/discharge control deviceaccording to claim 5.